Single-phase commutator-motor.



APPLICATION FILED MAR. 3, 1906'.

Patented July 20,190

, constructivcf elcments of a repulsion motor .Wlthtllfi QOIlStl-UMJIVG elements of a non-synnatingjcurrent'supplied to the rotor byway- YhLEBE ALFRED FYNN, or BLAGKHEAITH, ronnon, ENGLAND.-

smenrtrnasncom/rUrAToR-MoTon.

I Specification .of Letters Patent.

Patented .Tu1y 2 0, 1909.

- Application filed llamas, 1906. Serial No. 303,994.

phase commutator motors-which can start as I repulsion motorsTend ,ratc as induction motors, anl the power actor'-='and*torqueof which em -improved by ressing on the rotor an auxiliarylil; F. of suitable phase. It. therefore manometer s combining the chronous-induction motor, a'nd'having alteror the commutator'as described and claimed in my American Patent No. 777,198. Among other things it was shown in the paten-t reie-rred'te thatthe auxiliary E. M. F. required could be obtained from an EtUX'l'QfiIy winding disposed on the stator. This means for obtaining the auxiliary E. M. F. is by far the most convenient but. it entails certain disad vantages to removewhich is the ob ect of this invention. Thus inorder to reverse the direction. of rotation of such acompensated shunt induction motor 1t.would be necessary either to use an iueflicient stator 'iliary winding'can be made use winding (such as a distributed one) or to rovide two main stator windings one of The brushes could also be shifted for til/e urpose of reversing the direction of rotation ut this would be very objectionable-in'practice and would in addition necessitate two auxiliary stator windings in case the auxiliary E. Mil

was derived from anauxiliary stator winding. t

By the present invention these disadvantages are obviated by suitably combining with the said type of motor an eflicient main stator winding divided into two parts dis-' placed with regard. to each other.- These parts are so dis laced and. so connected that the direction 0 rotation. can be reversed by reversing the current in one or more parts of the stator Winding, whereby the same aimof {or both directions of Y rotation. One part of the stator winding is-thereiore according to this;

invention prefera'bl placed coaX-ially with "-'repu'lsion bros ALFRED Fawn,

which this E. M. F. is derived is preferably disposed coaxiall y with one or the other oi the two parts of the divided stator winding. This combination of elements produces a motor which can start with apowerful torque .in the one or other direction, can operate with a nearly constant speed while running in the one-or other direction, can he compensatcdto any desired extent when running in either direction while using stator windings of the most efficient type and while avoiding all idle windings in the machine.

-The accompanying drawings represent diagrammatically .a number of examples illustrating the nature of the invention.

In all cases 2 pole motors have been chosen as examples, but all the combinations illustrated can be applied without difficulty to multipolar motors. In all cases the rotor A (the armature) is supposed to be provided with a Gramme'ring winding and the brushes are supposed to rest directly on the winding.

Figure 1 shows the known primary form of the single-phase shunt induction motor, the characteristics of the shunt induction motor are imparted to the machine by the fact that the armature is shortcircuited by way of the commutator and along theistation-ary axes passing through R R and H H. Fig. 2 shows a singlc-phase shunt induction motorpossessing the features of this invention and the auxiliary E. M. F. for which is derived y from an outside source. Fig. 3 shows a single-phase shunt induction motor possessing the features of this invention, the auxiliary E. M. F. for whichis derived from a winding dis-posed on the stator and to which the characteristic of a shunt induction stationary short circuits R R and H H but rotor windingare shortcircuited independ ently of the commutator. Fig. 4 shows .a motor similar to that shown in Fig. 3. but where the rotor carries two windings, one of these being connected to the commutator and the other being adapted to be shortc-ircuited. Fig. 5 shows a motor possessing the s, or those which-are features of this'inventionand to which a motor is imparted not only loy means of thealso by the fact thatseveral points of the? shunt induction characteristic is imparted only by the fact that a number of rotor points are adapted to be shortcircuited in dependently of the commutator. Figs. 6 and 7 show a motor similar to that illustrated in Fig. 2 but where the auxiliary E.

M. F. is derived from the motor itself andthese figures particularly illustrate the mode of connecting up the machine for-running 10 the one or theother direction.

Before beginning the description of-the several examples given it will be well togive a short theory'of the shunt induction motor to which these improvements refer.

As soon as an asynchronous single-phase induction motor provided with a squirrel cage rotor has attained a sufficiently high number of revolutions, a (second or) secondary field is setup in this motor by rotation, which field is displaced in phase and space by about 90 degrees with regard to the primary field due to the stator. But the single-p,hase induction, motor with squirrel cage is only a special case of the primary form of the single-phase induction motor;

- this comprises, as is well known, a direct curs? rent armature which (for a 2'po le motor) is short-circuited along two axes stationary in s v ace and perpendicular to each other as is sliown diagrammatically in Fig. 1. By shortcircuiting the rotor along more and more axes one finally arrives at a totally short-circuited rotor in which the commutator can be dispensed with and one practical form of which is known as the squirrel cage rotor. If one of these axes, for instance that passing through the brushes R. coincities with the stator field axis then the sec 'ondary field set up'by rotation will be perpendicular to the primary field and will coincide :with the axis of the brushes H, the motor will then operate as a pure induction motor. If neither of the two axes coincide with the rimary field, then a secondary field will still be set up by rotation and the motor will not only operate as an induction motor but also partly as a repulsion motor. The two fields existing in such a motor are as regards phase displaced with regard to each other by practically 90 degrees. Now since a field always induces in a winding placed therein an E. M. F which lags by 90 degrees behind that field then in this case the primary field will induce in a winding coaxial with it an E. M. F. which is cophasal with the other, or second ary field, induced in the motor by rotation and vice versa. In case then that the auxiliary E. M. F. is to be obtained from the motor itself, ,the auxiliary winding is always to be dis osed (for the two pole motor shown. in Fig. 1 ap roximately in that field which is perpendicu ar to the one along the axis of which the auxiliary E. M. F. is to be impressed.

5 It may be stated generally that in order to compensate the motor (i. 6. improve its power factor) with the least expenditure of energy, the auxiliary E. M. F. to be impressed on the rotor by way of the commu-' tater should coincide in phase as nearly as possible with that field which traverses the rotor in normal operation (before the aux .iliary E. M. has been applied) approximately along that axis or direction along which the said auxiliary E. M. F. is to be impressed. The phase of this auxiliary E. M. F. may also be defined b saying that it should be of approximate y the same phase as that E. M. F. which is generated in the rotor by rotation and at .those points of the rotor winding (or commutator) at which the'auxiliary E. M. F. is applied. It is then to be understood that the rotor E. M. F. relerred to is generated by rotation in that leakage field the axis of which is approximately at right angles to the axis along which the auxiliary E. M. F. is impressed.

The motor shown in Fig. 2 comprises a stator winding divided into two groups S and S displaced by 180m degrees also a rotor provided with a winding connected to a commutator on which are disposed two sets of brushes. The one set R R is ada ted to be directly short-circuited and is p aced coaxiaily with the stator group S which contains the greatest number of turns. 1 ,The other'set of brushes H H is displaced by 180/11. degrees with regard to in. it and adapted to receive the auxiliary E. M. F. (E) which in this case is/derived from an outside source and impressed on the brushes H H by. way of the transformer T whiclrcan be re 'ulated by the switch K.

In order to start the motor the circuit of the brushes HTH. is opened or the auxiliary E. M. F. chosen relatively high. When up to speed this brush circuit is closed and the magnitude of the auxiliary E. M. F. is adjusted so as to give the required value of cos c i. e. of the power factor. The propor-- 110 tion of the turns in the stator windings S and S determines the starting torque. The relative direction of the current through these two windings determined the direction of rotation. The auxiliary E. M. F. is here derived by way of example from an ordinary asynchronous single-phase motor M with a squirrel cage rotor Q. The stator of-M carries two windings l) and D, the winding D is connected in arallel to the mains, the 120 winding D is disp aced with regard to the. first so as to yield an auxiliary E. M. F. as nearly as possible in phase with the secondary field of the motor or that field which is set up in the motor by rotation and which threads the rotor approximately in the direction of the brushes H H or in that direction in which the auxiliary E. M. F. is to be applied. After the motor has reached its in speed, all the brushes may be-so dis- 130 plied to the brushes H H ina placed as tobring the short-circuited brushes R into coincidence with the axis F of total magnetization produced by the stator windings. The auxiliary E. M. F. (E) when a have t e same phase as that of the E. M. supply.

- regulate the auxiliary wind' placed. by 180/11 degrees with respect to the brushes H'H to which the auxiliary The motor shown in Fig. 3 comprises the same elements as that shown in Fig.2. The

auxiliary E. M. F. applied to the brushes H H is however derived from an auxiliary N disposed on the stator and dis- E. M. F. is applied. A resistance W is here provided by W8. of example in order to E. M. F. If it isdesired to closethe H H circuit already at starting then the resistance must be chosen high and diminished with increasing speed.

shortcircuited gradually over the resistances X as shown in Fig. 3. These slip rings are shortcircuited preferably whenthe motor has reached its normal speed.

The motor shown in Fig. 4 comprises the same elements as that shown in Fig. 3. The auxiliary E. M. F. is however applied to those brushes R R which are used for starting and is derived from an auxiliary winding N disposed on the stator and the axis of which is displaced by 180/n degrees with respect to the axis through the brushes R R. The rotor carries two windings by way of example, the one I) connected to the, commutator, the other 0 adapted to be shortcireuited at the points 1, 2, 3. Means for shortcircuit ing these points are not'shown so as not to complicate the figure. Any known means may be used, for instance those shown. in Fig.

3. When starting the motor the brush circuit H H is left open at the switch P and the brushes R R shortcircuited by, means of switch K orclosed on the auxiliary winding N. When up to speed P is closed and K is adjusted so as to obtain the desired power factor. It ma be stated as a guide to the choice of the pliase of. the auxiliary E. M. F. when applied to the brushes R'R that it should be approximately in quadrature with the phase of the E. M. F. applied to the main stator winding.

The motor shown in Fig. 5 comprises the same elements as in the previous example with the exception however of the brushes H H which in this case have been left out. When these brushes are not used to convey the auxiliary E. M. F. into the rotor and when means are provided for shortcircuiting a rotor winding independently of the commutator then these brushes can be dis carded without robbing the motor of its shunt induction characteristics. In Fig. 5 the means for shortcircuiting a'rotor winding independently of the commutator are the same as shown in Fig. 3. For the purpose of regulating the circuit comprising the brushes R R a resistance is provided at W.

Figs. 6 and 7 show'motors identical in every respect with that illustrated by Fig. 3 with the exception however that no means are provided for shortcircuiting a ro'tor'windfingindependently of the commutator. These two figures illustrate the change of connections required in the stator windings in order to reverse the direction of rotation of the motor. I

What I claim and desire to secure by Letters Patent is 1. In aSingle-phase commutator motor, an inducing member, main winding on the inducing member consisting of two parts displaced by 180/n degrees and connected in series relation, an auxiliary winding on the inducing member, an induced member, means for introducing into the induced memher an auxiliary E. M. F. derived from. said 7 auxiliary winding and means for short-circuiting the induced member along at least one axis.

2. In a single-phase commutator motor, an inducing member, a main winding on the inducing member consisting of two parts displaced by ISO/n degrees and connected in series relation, an auxiliary winding on the inducing member coaxially disposed with,

reference to one part of the said main winding, an induced member, means for introducmg into the induced member an auxiliary E.

M. F. derived from said auxiliary winding and means for short-circuit ng the induced 1nember along at least one axis.

3. In a single-phase commutator motor, an inducing member, a main winding on the inducing member consisting of two parts displaced by 180/n degrees and connected in series relation, an auxiliary winding on the inducing member coax ially disposed with one part of the said main winding, an induced member, means for introducing into the induced member along an axis displaced by 180 /'n degrees with .n spect to the axis of said auxiliary Winding a1 auxiliary E. M. F. de-

rived from said auxil ary winding and means for 'short-circuiting the induced member along at least one ax s.

4. In a single-phase commutator motor,

an inducing member, a main winding on the inducing member'consisting of two parts displaced by /n degrees and connected in series relation, an auxiliary winding on the inducing member coaxially disposed with one part of the said main winding, an induced member, means for introducing into the induced member along an axis displaced by" ISO/n degrees with respect tothe axis of said auxiliary winding an auxiliary E. M. F. derived from said auxiliarywinding and means for short-circuiting the induced member along an axis coinciding with that of the said auxiliary winding. 5. A single-phase commutator motor comprising the combination of a stator, a main winding on the stator divided into two parts connected in series relation and displaced by 180/17, degrees with respect to each other, an 'auxiliary winding on the stator, a rotor, commutator, two sets of brushes on the commutator, means for short-circuiting one set of brushes, and means for connecting the other set of brushes to said auxiliary wind ing. I

6. A single-phasecommutator motor comprising the combination of a stator, a main winding on the stator divided into two parts connected in series relation and displaced by.

180/12 degrees, an auxiliary winding on the stator eoaxially disposed with reference to one part of the main. stator winding, a rotor, a commutator, two sets of brushes on the commutator displaced by 180/12, degrees, means for short-circuiting one set of brushes and means. for connecting the other set of brushes to said auxiliary winding.

7 A single-phase commutator motor comprising the combination of a stator, a main winding on the statordivided into two parts connected in series relation and displaced. by ISO/n degrees, an auxiliary winding on the stator coaxially disposed with one part of the main stator winding, a rotor, a commutator, two sets of brushes on the commutator one set being'coaxially disposed with the auxiliary stator winding and displaced by 180/ n degrees with respect to the other set of brushes, means for short-circuiting that set of brushes which is coaxi-ally disposed with said auxiliary winding, and means for connecting the other set to this auxiliary winding.

8. A single-phase commutatormotor comprising the combination of a stator, a main winding on the stator divided into two parts connected in series relation and displaced by 180/n degrees, an auxiliary winding on the stator, a rotor, a commutator, two sets of brushes on the commutator, means for shortcircuiting one set of brushes, means for conneotingthe other set of brushes to said auxiliary winding and means for short-circuitmg a number of points or the rotor windings independently of tlie'commutator.

9. A single-phase commutator motor comprising the combination of a stator, a main winding on the stator divided into two parts of brushes which is coaxially disposed-with said auxiliary winding, means for connecting the other set of brushes to said auxiliary winding and means for short-circuiting a number of eints of the rotor windings independently f the commutator.

In witness whereof, I have hereunto signed my name in the presence of two subscribing witnesses. g I

VALERE ALFRED FYNN. Witnesses: 4 R BERT M. SPEARPOINT, H. D. JAME'SON. 

